Method for comprehensively recycling lead and zinc containing blast furnace dust

Abstract

The invention discloses a method for comprehensively recycling lead and zinc containing blast furnace dust and belongs to the technical field of iron and steel smelting. The method comprises the following steps: the step of batching: evenly mixing reclaimed lead and zinc containing blast furnace dust and a carbon powder agent according to the weight ratio of 10 to 1-3 to prepare pellets; the step of removing lead and zinc at a high temperature: adding the pellets into a rotary kiln from a kiln tail, spraying fuel from a kiln head to heat the pellets to reach the temperature of 900 to 1300 DEG C and smelting for 30 to 50 min, after smelting, discharging an obtained lead and zinc removed iron containing material from the kiln head and cooling to reach a normal temperature, and discharging dust and gas from the kiln tail; the step of lead and zinc dust recycling: collecting and sending the gas and the dust discharged from the kiln tail of the rotary kiln into a cyclone dust collector to obtain lead and zinc containing dust through catching, and externally discharging residual smoke; and the step of magnetic separation of an iron containing material: carrying out magnetic separation on the lead and zinc removed iron containing material so as to obtain iron ore concentrate and tailings. The method provided by the invention is characterized in that the process is simple, more than 90 percent of lead and zinc in the lead and zinc containing blast furnace dust can be effectively removed, iron containing dust, lead and zinc can be comprehensively recycled, and energy conservation and emission reduction can be achieved.

Description

technical field [0001] The invention belongs to the technical field of iron and steel smelting, and specifically relates to a method for comprehensively recycling blast furnace lead-zinc-containing dust with simple process, high removal rate of lead and zinc in dust, high resource utilization rate, energy saving and emission reduction. Background technique [0002] Blast furnace dust containing lead and zinc is also commonly known as blast furnace ash or blast furnace gas ash. Generally speaking, the output of dust in iron and steel enterprises is 8-12% of steel output, the mass fraction of iron in furnace dust is 30-45%, and the mass fraction of carbon is 10%. ~40%. Since the dust produced by blast furnaces using ores with high zinc and lead content contains a certain proportion of lead and zinc elements, it can be well applied to ordinary blast furnace dust for sintering, but the use of dust with high lead and zinc content is more troublesome. , and the problem is becomin...

AI Technical Summary

Problems solved by technology

The physical method is mainly to dry or wet separate the dust through flotation, gravity, magnetic separation and other beneficiation methods, or use hydrocyclone technology to carry out wet classification according to particle size. The main purpose is to obtain qualified iron concentrate, basically no Considering the utilization of lead and zinc, and most of the physical methods include flotation carbon removal process, a large amount of water consumption and subsequent treatment in the flotation process is a problem, and there are also great disadvantages, and the dust in the dust A part of zinc exists in the form of zinc ferrite composite oxide, which makes the zinc content in the iron concentrate after separation mostly exceed the standard. Due to this difficult problem, many researches in this field at home and abroad are at a standstill

The wet process is mainly used by foreign iron and steel enterprises to deal with high-zinc dust with a zinc content greater than 15%, but there are still low zinc and lead leaching rates, and the leaching slag is difficult to be recycled as raw materials for steel plants, and it cannot meet the requirements of the Environmental Protection Law. stacking requirements; and there are generally too many unit operations, the consumption of leaching agents is high, and the cost is high; the equipment is severely corroded. Most of the operating conditions are relatively harsh; they are sensitive to raw materials, making it difficult to optimize the process; sulfur and chlorine introduced during the treatment process are likely to cause new environmental pollution; low efficiency and other defects, so the use is relatively limited

Pyrotechnic process is currently the most feasible method to deal with low-zinc dust, but the sulfide roasting has strict requirements on raw materials (does not contain a lot of carbon), serious sulfur pollution, high sulfur content in slag and is not suitable as raw material for steel plants; chlorine Chemical roasting has too much corrosion on equipment; direct sintering method mixes dry and wet dust directly with sintering raw materials for sintering, and the sintered ore produced is used as blast furnace raw material; although the pellet sintering method solves the problem of poor sintering performance caused by too fine dust , but the pellet binder is added, which reduces the grade of iron concentrate after roasting

The direct sintering process in the prior art has many types of dust, so it is difficult to accurately measure the ingredients; in addition, uneven mixing will also cause sintering composition segregation; in addition, adding sintering raw materials such as binders not only increases the cost, And reduce the grade of iron ore concentrate after roasting

Most of the pyrotechnics in the prior art are purely for removing harmful metals such as lead and zinc in the dust, but they are seldom able to be effectively recycled and utilized, which not only wastes lead and zinc resources, but also pollutes the environment

Images